The present invention pertains to a device for coating an essentially flat, disk-like substrate with the aid of cathodic sputtering. The device comprises an essentially cylindrical transport chamber, including a round disk-shaped lid, a bottom plate extending in a plane parallel to it and an annular housing part connecting the two parts in a pressure-tight manner and a certain distance apart and forming the side wall, and with a vacuum pump connected to the transport chamber and with an opening that can be closed off by a plate provided in the lid of the transport chamber for inserting and removing the substrates and with a coating chamber connected to the lid, containing the cathode and connected by an opening in the lid to the transport space and with a substrate carrier seated so as to be able to rotate in the transport chamber.
A device for coating flat, disk-like substrates is known for U.S. Pat. No. 3,874,525 which has a coating chamber in which a two-armed gripping tool is seated so as to rotate about a vertical axis. This two-armed tool has forks at its diametrically opposing ends which can be moved in a mutually opposite sense in a vertical plane with the aid of a rack drive with a drive motor. Furthermore, two consoles are placed in the coating chamber, one of which is arranged beneath a transfer channel or coating chamber and the other on the side facing this console underneath the electron gun.
This known device has the disadvantage that the two-armed gripping tool is constructed in a comparatively elaborate manner and also does not operate very reliably, since the complicated gear drive produces wear fragments. With this device there also exists the danger that the workpiece may not be gripped properly by the fork-shaped tool and then will be either picked up in a tilted manner or come completely loose from the tool and then fall to the bottom surface of the coating chamber, which will necessarily lead to a blockage or the malfunction of the entire system. Finally, the known device requires a large overall height, which makes an undesirably large coating chamber necessary.
Also known in this art is a device shown in U.S. Pat. No. 4,548,699 in which an essentially cylindrical coating chamber is provided, consisting of a circular disk-shaped lid and bottom plate of the same type, wherein the lid and the bottom plate are solidly connected by a hollow cylindrical or annular side part. Arranged therein is a circular disk-shaped rotary plate for holding and guiding the substrates and an additional pressure plate. These can be displaced in the direction of the lid and, after the displacement, close off a transfer opening provided in the lid to thereby fit pressure-tight together with the lid. This known device has a complicated structure and operates relatively slowly, particularly since the wafers must be taken up by spring elements and the transfer opening must be closed off by an additional locking plate that pivots about a bolt arranged transverse to the axis of rotation.
Also known is a device (German Patent No. 37 16 498) for transferring an essentially flat workpiece into and out of an evacuated coating chamber formed from a flat, circular disk-shaped lid and a flat, circular disk-shaped bottom plate extending in a plane parallel to it and of an annular side part connecting both parts pressure-tight and holding them a distance apart. A circular disk-shaped rotary plate is seated in the coating chamber so as to be able to rotate for holding the workpiece during the coating process. The device serves for feeding the workpiece into and returning it from the area of a coating source arranged at the lid of the coating chamber for the purpose of treating the workpiece. A coating device arranged on the lid of the coating chamber is provided with one or more lid-shaped workpiece carriers, with the aid of which the workpieces can be brought into a position adjacent to the opening of the coating chamber. From there, the opening can be closed off from above by the workpiece carrier and from the bottom by a lifting plate that is held and guided on a rotary plate seated so as to rotate inside the coating chamber. The workpiece carrier then can be pressed against the lid of the coating chamber by a lifting cylinder supported on the coating device and the lifting plate can be similarly pressed by a lifting device mounted on the bottom plate.
Finally a vacuum coating system for vapor deposition of thin-films on substrates is known from U.S. Pat. No. 3,915,117. The system has an entrance chamber, additional chambers for treating or coating substrates and with an exit chamber, as well as a conveyance unit arranged in an evacuated main chamber for conveying the substrates through the chambers. Sealing devices are provided for temporary sealing between the aforesaid chambers and the main chamber. The conveyance unit has frames for accommodating the material to be coated that are arranged around a common axis and can be pivoted about it, wherein such a frame itself forms part of the wall of treatment chamber, namely, the entry and exit chamber and a vapor-deposition chamber in at least two treatment positions, namely, an entry and exit position and a vapor-deposition position. In at least one of these treatment positions, a movable valve plate is provided for closing off an end face of the frame forming one part of the treatment chamber.
Accordingly, it is an object of the present invention to provide a device of the type as described such that the time for changing the cathode can be reduced to a minimum.
It is a further object of the present invention that the device should be simpler in structure than those of the past and thus also more economical to produce and also more reliable in its operation.
Yet another object of the present invention is to reduce the overall space required by the device and in particular, by foregoing additional drive units in the peripheral area of the transport chamber.